Monte Carlo sim of the inescapable, eternally relevant frog riddle.

frog.cpp

#include <stdio.h>
#include <random>

float random_float() {
	static std::random_device rd;
	static std::default_random_engine re;
	static std::uniform_real_distribution<float> urd(0, 1);

	return urd(re);
}

float random_float(float max) {
	return random_float() * max;
}

float random_float(float min, float max) {
	return random_float() * (max - min) + min;
}

bool random_bool() {
	return random_float() < 0.5f;
}

int main() {
	int iters = 10000000;

	//chance: the percent chance that a male frog will croak once within a given time frame
	for (int chance = 5; chance <= 100; chance += 5) {
		int matches = 0;
		int lives1 = 0;
		int lives2 = 0;

		for (int i = 0; i < iters; ++i) {
			//randomly pick gender of all frogs
			bool male0 = random_bool(); //side A
			bool male1 = random_bool(); //side B
			bool male2 = random_bool(); //side B

			//determine if each frog croaks or not
			bool croak0 = male0? random_float(100) < chance : 0;
			bool croak1 = male1? random_float(100) < chance : 0;
			bool croak2 = male2? random_float(100) < chance : 0;

			//eliminate situations that don't match the one supposed in the video
			//(no croak from side A, and exactly 1 croak from side B)
			if (croak0 || (croak1 && croak2) || (!croak1 && !croak2)) {
				continue;
			}

			//tally up the stats
			matches += 1;
			if (!male0) {
				lives1 += 1;
			}
			if (!male1 || !male2) {
				lives2 += 1;
			}
		}

		//human-readable output
		printf("frog croak chance: %3d%%   scenario chance: %6.2f%%   "
			   "side A: %6.2f%% survival   side B: %6.2f%% survival\n",
				chance, matches / (float)iters * 100,
				lives1 / (float)matches * 100, lives2 / (float)matches * 100);

		//csv output (for them sick graphs, yo)
		// printf("%d,%f,%f,%f\n", chance, matches / (float)iters * 100,
		// 		lives1 / (float)matches * 100, lives2 / (float)matches * 100);

		//makes the input appear line by line, to give a better sense of progress
		fflush(stdout);
	}

	return 0;
}

output.txt

frog croak chance:   5%   scenario chance:   4.76%   side A:  51.34% survival   side B:  51.26% survival
frog croak chance:  10%   scenario chance:   9.03%   side A:  52.60% survival   side B:  52.63% survival
frog croak chance:  15%   scenario chance:  12.83%   side A:  54.13% survival   side B:  54.07% survival
frog croak chance:  20%   scenario chance:  16.20%   side A:  55.54% survival   side B:  55.56% survival
frog croak chance:  25%   scenario chance:  19.14%   side A:  57.17% survival   side B:  57.12% survival
frog croak chance:  30%   scenario chance:  21.68%   side A:  58.81% survival   side B:  58.84% survival
frog croak chance:  35%   scenario chance:  23.82%   side A:  60.61% survival   side B:  60.61% survival
frog croak chance:  40%   scenario chance:  25.62%   side A:  62.52% survival   side B:  62.53% survival
frog croak chance:  45%   scenario chance:  27.04%   side A:  64.51% survival   side B:  64.51% survival
frog croak chance:  50%   scenario chance:  28.12%   side A:  66.68% survival   side B:  66.67% survival
frog croak chance:  55%   scenario chance:  28.91%   side A:  68.97% survival   side B:  68.97% survival
frog croak chance:  60%   scenario chance:  29.40%   side A:  71.47% survival   side B:  71.39% survival
frog croak chance:  65%   scenario chance:  29.60%   side A:  74.05% survival   side B:  74.07% survival
frog croak chance:  70%   scenario chance:  29.57%   side A:  76.90% survival   side B:  76.89% survival
frog croak chance:  75%   scenario chance:  29.28%   side A:  79.95% survival   side B:  79.98% survival
frog croak chance:  80%   scenario chance:  28.81%   side A:  83.35% survival   side B:  83.34% survival
frog croak chance:  85%   scenario chance:  28.10%   side A:  86.96% survival   side B:  86.97% survival
frog croak chance:  90%   scenario chance:  27.24%   side A:  90.92% survival   side B:  90.88% survival
frog croak chance:  95%   scenario chance:  26.18%   side A:  95.24% survival   side B:  95.21% survival
frog croak chance: 100%   scenario chance:  24.97%   side A: 100.00% survival   side B: 100.00% survival